Template Function Acts::estimateTrackParamsFromSeed(spacepoint_iterator_t, spacepoint_iterator_t)

Function Documentation

template<typename spacepoint_iterator_t>
std::optional<BoundVector> Acts::estimateTrackParamsFromSeed(spacepoint_iterator_t spBegin, spacepoint_iterator_t spEnd)

Estimate the track parameters on the xy plane from at least three space points.

It assumes the trajectory projection on the xy plane is a circle, i.e. the magnetic field is along global z-axis.

The method is based on V. Karimaki NIM A305 (1991) 187-191: https://doi.org/10.1016/0168-9002(91)90533-V

  • no weights are used in Karimaki’s fit; d0 is the distance of the point of closest approach to the origin, 1/R is the curvature, phi is the angle of the direction propagation (counter clockwise as positive) at the point of cloest approach.

Return

optional bound track parameters with the estimated d0, phi and 1/R stored with the indices, eBoundLoc0, eBoundPhi and eBoundQOverP, respectively. The bound parameters with other indices are set to zero.

Template Parameters

  • spacepoint_iterator_t: The type of space point iterator

Parameters

  • spBegin: is the begin iterator for the space points

  • spEnd: is the end iterator for the space points